Kolkata, May 25 -- A team of scientists has called for the integration of hydrogeochemical science, agricultural innovation and socio-economic analysis to tackle arsenic contamination across the Indo-Gangetic Plain (IGP).
The researchers warned that groundwater irrigation in the moribund Bengal delta is sustaining contamination through a soil-water recycling loop that continually leaches arsenic from native soils back into aquifers. Arsenic also reaches people through cooked food such as rice and bread, adding to the health burden. Long-term exposure to arsenic-contaminated water has been linked to skin, lung, kidney and bladder cancers, as well as coronary heart disease, bronchiectasis, hyperkeratosis and arsenicosis.
"Our arsenic mitigation strategies have shown that monsoonal paddy cultivation in West Bengal highlights the crucial role of rainwater in diluting arsenic, reducing its bioavailability and uptake by paddy plants," said Antara Das of the Department of Economics at FLAME University, Pune.
"We found that rice grown during the monsoon season had lower arsenic concentrations than Boro rice, making it a relatively safer agricultural practice in arsenic-affected regions," Das added.
According to Arnab Majumdar of the Department of Life Sciences, Imperial College London, aerobic rice cultivation offers another promising solution.
"In aerobic systems, rice is grown under unsaturated or non-flooded conditions, which reduces arsenic mobilisation in the soil. Since arsenic is more soluble under anaerobic, waterlogged conditions, shifting to aerobic cultivation significantly lowers arsenic uptake by rice plants," explained Majumdar.
Examinations conducted by the team showed that aerobic cultivation reduced total arsenic in rice grains by 62 per cent and inorganic arsenic by nearly 68 per cent.
"The study highlights aerobic farming with minimal irrigation as an effective strategy to reduce arsenic risks in rice," Das said. Alternate Wetting and Drying (AWD) - a water-management technique in which fields are periodically dried instead of being continuously flooded - emerged as another key intervention. The practice reduces arsenic bioavailability and uptake in rice while conserving water and improving productivity in the Gangetic plain.
Trials reported up to a 61 per cent reduction in grain arsenic concentration, along with a 29.25 per cent increase in grain yield under AWD regimes.
"The study further showed that continuous sprinkler irrigation over seven years reduced total arsenic in rice grains to one-sixth of its initial concentration under a waterlogged system," said Tarit Roy Chowdhury of the School of Environmental Studies, Jadavpur University. "Sprinkler irrigation significantly increased rice yields while using 55 per cent less water than flooding. It also reduced arsenic accumulation in grains, particularly when combined with compost, effectively eliminating the risk regardless of tillage methods," he added.
The researchers said the arsenic mitigation strategies are aligned with the United Nations Sustainable Development Goals (SDGs). Their findings have been published in the Springer journal Water, Air, & Soil Pollution.
Published by HT Digital Content Services with permission from Millennium Post.